With ongoing developments in microcircuitry and multimedia technology, camera modules have become widely used in a variety of consumer electronic devices, such as smart phones, notebook computers, digital cameras, and personal digital assistants (PDAs). A typical camera module includes at least one lens module and an image sensor. In addition, there is a growing demand for developing more camera modules with multiple functions, such as camera modules having auto-focus function. A shape memory alloy (SMA) based actuator utilizing shape-memory alloy is widely used in a camera module to achieve the auto-focus function.